Response to Corticosteroids and Cytotoxic Drugs in a Case of Idiopathic Hypereosinophilic Syndrome with Predominantly Elevated Eosinophils and Multiple Clinical Manifestations

In the present case study, a 42-year-old Chinese woman fulfilling the WHO criteria for idiopathic hypereosinophilic syndrome (IHES) who exhibited clinical manifestations of eosinophilic infiltration of multiple tissues including the lungs, heart, central and peripheral nervous system, gastrointestinal tract, spleen, liver and unexplained clinical findings is described. Laboratory investigations revealed the topmost white blood cell and eosinophil that were 150 × 10⁹/L and 136 × 10⁹/L (90.6 %), respectively. To our knowledge, such a large number of eosinophils has rarely been reported, and all reactive causes of hypereosinophilia were excluded. Treatment with cytotoxic chemotherapy, prednisone and dexamethasone was not beneficial. The patient showed a remarkable hematological response when methylprednisolone pulse therapy was initiated when progression of respiratory symptoms occurred, but without clinical remission. The patient subsequently died. We consider that her critical organ damage and poor prognosis were related to the large number of eosinophils and delayed effective anti-eosinophilic therapy after severe organ damage occurred. This case highlights the clinical importance of methylprednisolone pulse therapy which should be initiated without delay once the diagnosis of IHES is made.